Planetary transmissions having a stationary gear member and clutched input members

ABSTRACT

The family of transmissions has a plurality of members that can be utilized in powertrains to provide at least eight forward speed ratios and one reverse speed ratio. The transmission family members include three planetary gear sets having seven torque-transmitting mechanisms, two interconnecting members, and a grounded planetary gear member. The powertrain includes an engine that is selectively connectable to at least one of the planetary gear members and an output member that is continuously connected with another one of the planetary gear members. The seven torque-transmitting mechanisms provide interconnections between various gear members, the input shaft and the transmission housing, and are operated in combinations of three to establish at least eight forward speed ratios and at least one reverse speed ratio.

TECHNICAL FIELD

The present invention relates to a family of power transmissions havingthree planetary gear sets that are controlled by seventorque-transmitting devices to provide at least eight forward speedratios and at least one reverse speed ratio.

BACKGROUND OF THE INVENTION

Passenger vehicles include a powertrain that is comprised of an engine,multi-speed transmission, and a differential or final drive. Themulti-speed transmission increases the overall operating range of thevehicle by permitting the engine to operate through its torque range anumber of times. The number of forward speed ratios that are availablein the transmission determines the number of times the engine torquerange is repeated. Early automatic transmissions had two speed ranges.This severely limited the overall speed range of the vehicle andtherefore required a relatively large engine that could produce a widespeed and torque range. This resulted in the engine operating at aspecific fuel consumption point during cruising, other than the mostefficient point. Therefore, manually-shifted (countershafttransmissions) were the most popular.

With the advent of three- and four-speed automatic transmissions, theautomatic shifting (planetary gear) transmission increased in popularitywith the motoring public. These transmissions improved the operatingperformance and fuel economy of the vehicle. The increased number ofspeed ratios reduces the step size between ratios and therefore improvesthe shift quality of the transmission by making the ratio interchangessubstantially imperceptible to the operator under normal vehicleacceleration.

It has been suggested that the number of forward speed ratios beincreased to six or more. Six-speed transmissions are disclosed in U.S.Pat. No. 4,070,927 issued to Polak on Jan. 31, 1978; and U.S. Pat. No.6,422,969 issued to Raghavan and Usoro on Jul. 23, 2002.

Six-speed transmissions offer several advantages over four- andfive-speed transmissions, including improved vehicle acceleration andimproved fuel economy. While many trucks employ power transmissionshaving six or more forward speed ratios, passenger cars are stillmanufactured with three- and four-speed automatic transmissions andrelatively few five or six-speed devices due to the size and complexityof these transmissions.

Seven-speed transmissions are disclosed in U.S. Pat. No. 6,623,397issued to Raghavan, Bucknor and Usoro. Eight speed transmissions aredisclosed in U.S. Pat. No. 6,425,841 issued to Haka. The Hakatransmission utilizes three planetary gear sets and six torquetransmitting devices, including two brakes and two clutches, to provideeight forward speed ratios and a reverse speed ratio. One of theplanetary gear sets is positioned and operated to establish two fixedspeed input members for the remaining two planetary gear sets. Seven-,eight- and nine-speed transmissions provide further improvements inacceleration and fuel economy over six-speed transmissions. However,like the six-speed transmissions discussed above, the development ofseven-, eight- and nine-speed transmissions has been precluded becauseof complexity, size and cost.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved familyof transmissions having three planetary gear sets controlled to provideat least eight forward speed ratios and at least one reverse speedratio.

In one aspect of the present invention, the family of transmissions hasthree planetary gear sets, each of which includes a first, second andthird member, which members may comprise a sun gear, a ring gear, or aplanet carrier assembly member, in any order.

In referring to the first, second and third gear sets in thisdescription and in the claims, these sets may be counted “first” to“third” in any order in the drawings (i.e., left to right, right toleft, etc.).

In another aspect of the present invention, the planetary gear sets maybe of the single pinion-type or of the double pinion-type.

In yet another aspect of the present invention, a first member of thefirst planetary gear set is continuously interconnected with a firstmember of the second planetary gear set through a first interconnectingmember.

In still another aspect of the present invention, a second member of thefirst planetary gear set is continuously interconnected with a secondmember of the second planetary gear set through a second interconnectingmember.

In a further aspect of the present invention, a first member of thethird planetary gear set is continuously connected with a stationarymember (transmission case).

In yet a further aspect of the invention, each family memberincorporates an output shaft which is continuously connected with atleast one member of the planetary gear sets, and an input shaft which isnot continuously connected with any member of the planetary gear setsbut is selectively connectable with at least one member of the planetarygear sets through at least one of seven torque-transmitting mechanisms.

In still a further aspect of the invention, a first torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thethird planetary gear set with the input shaft.

In another aspect of the invention, a second torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thefirst or second planetary gear set with the input shaft.

In a still further aspect of the invention, a third torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thefirst, second or third planetary gear set with the input shaft or withanother member of the first, second or third planetary gear set.

In a still further aspect of the invention, a fourth torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thethird planetary gear set with a member of the first or second planetarygear set.

In a still further aspect of the invention, a fifth torque-transmittingmechanism, such as a clutch, selectively connects a member of the firstor second planetary gear set with a member of the third planetary gearset. Alternatively, the fifth torque-transmitting mechanism, such as abrake, selectively connects a member of the first or second planetarygear set with the stationary member (transmission case).

In still another aspect of the invention, a sixth torque-transmittingmechanism, such as a clutch, selectively connects a member of the firstor second planetary gear set with a member of the first, second or thirdplanetary gear set. Alternatively, the sixth torque-transmittingmechanism, such as a brake, selectively connects a member of the firstor second planetary gear set with the stationary member (transmissionhousing).

In still another aspect of the invention, a seventh torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thefirst, second or third planetary gear set with another member of thefirst, second or third planetary gear set. Alternatively, the seventhtorque-transmitting mechanism, such as a brake, selectively connects amember of the first, second or third planetary gear set with thestationary member (transmission case).

In still another aspect of the invention, the seven torque-transmittingmechanisms are selectively engageable in combinations of three to yieldat least eight forward speed ratios and at least one reverse speedratio.

The above objects and other objects, features, and advantages of thepresent invention are readily apparent from the following detaileddescription of the best modes for carrying out the invention when takenin connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a schematic representation of a powertrain including aplanetary transmission incorporating a family member of the presentinvention;

FIG. 1 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 1 a;

FIG. 2 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 2 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 2 a;

FIG. 3 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 3 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 3 a;

FIG. 4 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 4 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 4 a;

FIG. 5 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 5 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 5 a;

FIG. 6 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 6 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 6 a;

FIG. 7 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 7 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 7 a;

FIG. 8 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 8 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 8 a;

FIG. 9 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 9 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 9 a;

FIG. 10 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 10 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 10 a;

FIG. 11 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 11 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 11 a;

FIG. 12 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 12 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 12 a;

FIG. 13 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention; and

FIG. 13 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 13 a.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, wherein like characters represent the same orcorresponding parts throughout the several views, there is shown in FIG.1 a a powertrain 10 having a conventional engine 12, a planetarytransmission 14, and a conventional final drive mechanism 16.

The planetary transmission 14 includes an input shaft 17 continuouslyconnected with the engine 12, a planetary gear arrangement 18, and anoutput shaft 19 continuously connected with the final drive mechanism16. The planetary gear arrangement 18 includes three planetary gear sets20, 30 and 40.

The planetary gear set 20 includes a sun gear member 22, a ring gearmember 24, and a planet carrier assembly 26. The planet carrier assembly26 includes a plurality of pinion gears 27 rotatably mounted on acarrier member 29 and disposed in meshing relationship with both the sungear member 22 and the ring gear member 24.

The planetary gear set 30 includes a sun gear member 32, a ring gearmember 34, and a planet carrier assembly member 36. The planet carrierassembly member 36 includes a plurality of pinion gears 37 rotatablymounted on a carrier member 39 and disposed in meshing relationship withboth the sun gear member 32 and the ring gear member 34.

The planetary gear set 40 includes a sun gear member 42, a ring gearmember 44, and a planet carrier assembly member 46. The planet carrierassembly member 46 includes a plurality of pinion gears 47 rotatablymounted on a carrier member 49 and disposed in meshing relationship withboth the sun gear member 42 and the ring gear member 44.

The planetary gear arrangement also includes seven torque-transmittingmechanisms 50, 52, 54, 56, 57, 58 and 59. The torque-transmittingmechanisms 50, 52, 54, 56 and 57 are rotating-type torque-transmittingmechanisms, commonly termed clutches. The torque-transmitting mechanisms58 and 59 are stationary-type torque transmitting mechanisms, commonlytermed brakes or reaction clutches.

The input shaft 17 is not continuously connected with any planetary gearmember. The output shaft 19 is continuously connected with the planetcarrier assembly member 26. The ring gear member 24 is continuouslyconnected with the planet carrier assembly member 36 through theinterconnecting member 70. The planet carrier assembly member 26 iscontinuously connected with the ring gear member 34 through theinterconnecting member 72.

The planet carrier assembly member 36 is selectively connectable withthe input shaft 17 through the clutch 50. The planet carrier assemblymember 46 is selectively connectable with the input shaft 17 through theclutch 52. The ring gear member 44 is selectively connectable with theinput shaft 17 through the clutch 54. The sun gear member 32 isselectively connectable with the planet carrier assembly member 46through the clutch 56. The sun gear member 32 is selectively connectablewith the ring gear member 44 through the clutch 57. The ring gear member24 is selectively connectable with the transmission housing 60 throughthe brake 58. The sun gear member 22 is selectively connectable with thetransmission housing 60 through the brake 59.

As shown in FIG. 1 b, and in particular the truth table disclosedtherein, the torque-transmitting mechanisms are selectively engaged incombinations of three to provide eight forward speed ratios and threereverse speed ratios.

The reverse speed ratio (Reverse) is established with the engagement ofthe clutches 54, 56 and the brake 58. The clutch 54 connects the ringgear member 44 with the input shaft 17. The clutch 56 connects the sungear member 32 with the planet carrier assembly member 46. The brake 58connects the ring gear member 24 with the transmission housing 60. Thering gear member 44 rotates at the same speed as the input shaft 17. Theplanet carrier assembly member 46 rotates at the same speed as the sungear member 32. The sun gear member 42 does not rotate. The speed of theplanet carrier assembly member 46 is determined from the speed of thering gear member 44 and the ring gear/sun gear tooth ratio of theplanetary gear set 40. The planet carrier assembly member 36 and thering gear member 24 do not rotate. The ring gear member 34 and theplanet carrier assembly member 26 rotate at the same speed as the outputshaft 19. The ring gear member 34, and therefore the output shaft 19,rotates at a speed determined from the speed of the sun gear member 32and the ring gear/sun gear tooth ratio of the planetary gear set 30. Thenumerical value of the reverse (Reverse) speed ratio is determinedutilizing the ring gear/sun gear tooth ratios of the planetary gear sets30 and 40.

The second reverse speed ratio (Reverse′) is established with theengagement of the clutches 52, 56 and the brake 58. The clutch 52connects the planet carrier assembly member 46 with the input shaft 17.The clutch 56 connects the planet carrier assembly member 46 with thesun gear member 32. The brake 58 connects the ring gear member 24 withthe transmission housing 60. The planet carrier assembly member 46 andthe sun gear member 32 rotate at the same speed as the input shaft 17.The planet carrier assembly member 36 and the ring gear member 24 do notrotate. The ring gear member 34 and the planet carrier assembly member26 rotate at the same speed as the output shaft 19. The ring gear member34, and therefore the output shaft 19, rotates at a speed determinedfrom the speed of the sun gear member 32 and the ring gear/sun geartooth ratio of the planetary gear set 30. The numerical value of thesecond reverse speed ratio (Reverse′) is determined utilizing the ringgear/sun gear tooth ratio of the planetary gear set 30.

The third reverse speed ratio (Reverse″) is established with theengagement of the clutches 52, 57 and the brake 58. The clutch 52connects the planet carrier assembly member 46 with the input shaft 17.The clutch 57 connects the ring gear member 44 with the sun gear member32. The brake 58 connects the ring gear member 24 with the transmissionhousing 60. The planet carrier assembly member 46 rotates at the samespeed as the input shaft 17. The sun gear member 42 does not rotate. Thering gear member 44 rotates at the same speed as the sun gear member 32.The ring gear member 44 rotates at a speed determined from the speed ofthe planet carrier assembly member 46 and the ring gear/sun gear toothratio of the planetary gear set 40. The planet carrier assembly member36 and the ring gear member 24 do not rotate. The ring gear member 34and the planet carrier assembly member 26 rotate at the same speed asthe output shaft 19. The ring gear member 34, and therefore the outputshaft 19, rotates at a speed determined from the speed of the sun gearmember 32 and the ring gear/sun gear tooth ratio of the planetary gearset 30. The numerical value of the second reverse speed ratio (Reverse″)is determined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 30 and 40.

The first forward speed ratio is established with the engagement of theclutches 54, 56 and the brake 59. The clutch 54 connects the ring gearmember 44 with the input shaft 17. The clutch 56 connects the sun gearmember 32 with the planet carrier assembly member 46. The brake 59connects the sun gear member 22 with the transmission housing 60. Thering gear member 44 rotates at the same speed as the input shaft 17. Theplanet carrier assembly member 46 rotates at the same speed as the sungear member 32. The sun gear member 42 does not rotate. The planetcarrier assembly member 46 rotates at speed determined from the speed ofthe ring gear member 44 and the ring gear/sun gear tooth ratio of theplanetary gear set 40. The planet carrier assembly member 36 rotates atthe same speed as the ring gear member 24. The ring gear member 34rotates at the same speed as the planet carrier assembly member 26. Thering gear member 34 rotates at a speed determined from the speed of theplanet carrier assembly member 36, the speed of the sun gear member 32and the ring gear/sun gear tooth ratio of the planetary gear set 30. Thesun gear member 22 does not rotate. The planet carrier assembly member26 rotates at the same speed as the output shaft 19. The planet carrierassembly member 26, and therefore the output shaft 19, rotates at aspeed determined from the speed of the ring gear member 24 and the ringgear/sun gear tooth ratio of the planetary gear set 20. The numericalvalue of the first forward speed ratio is determined utilizing the ringgear/sun gear tooth ratios of the planetary gear sets 20, 30 and 40.

The second forward speed ratio is established with the engagement of theclutches 54, 57 and the brake 59. The clutch 54 connects the ring gearmember 44 with the input shaft 17. The clutch 57 connects the ring gearmember 44 with the sun gear member 32. The brake 59 connects the sungear member 22 with the transmission housing 60. The ring gear member 44and the sun gear member 32 rotate at the same speed as the input shaft17. The sun gear member 42 does not rotate. The planet carrier assemblymember 46 rotates at the same speed as the ring gear member 24. The ringgear member 34 rotates at the same speed as the planet carrier assemblymember 26. The ring gear member 34 rotates at a speed determined fromthe speed of the planet carrier assembly member 36, the speed of the sungear member 32 and the ring gear/sun gear tooth ratio of the planetarygear set 30. The sun gear member 22 does not rotate. The planet carrierassembly member 26 rotates at the same speed as the output shaft 19. Theplanet carrier assembly member 26, and therefore the output shaft 19,rotates at a speed determined from the speed of the ring gear member 24and the ring gear/sun gear tooth ratio of the planetary gear set 20. Thenumerical value of the second forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratios of the planetary gear sets20 and 30.

The third forward speed ratio is established with the engagement of theclutches 52, 57 and the brake 59. The clutch 52 connects the planetcarrier assembly member 46 and the input shaft 17. The clutch 57connects the ring gear member 44 with the sun gear member 22. The brake59 connects the sun gear member 22 with the transmission housing 60. Theplanet carrier assembly member 46 rotates at the same speed as the inputshaft 17. The sun gear member 42 does not rotate. The ring gear member44 rotates at the same speed as the sun gear member 32. The ring gearmember 44 rotates at a speed determined from the speed of the planetcarrier assembly member 46 and the ring gear/sun gear tooth ratio of theplanetary gear set. 40. The planet carrier assembly member 36 rotates atthe same speed as the ring gear member 24. The ring gear member 34rotates at the same speed as the planet carrier assembly member 26. Thering gear member 34 rotates at a speed determined from the speed of theplanet carrier assembly member 36, the speed of the sun gear member 32and the ring gear/sun gear tooth ratio of the planetary gear set 30. Thesun gear member 22 does not rotate. The planet carrier assembly member26 rotates at the same speed as the output shaft 19. The planet carrierassembly member 26, and therefore the output shaft 19, rotates at aspeed determined from the speed of the ring gear member 24 and the ringgear/sun gear tooth ratio of the planetary gear set 20. The numericalvalue of the third forward speed ratio is determined utilizing the ringgear/sun gear tooth ratios of the planetary gear sets 20, 30 and 40.

The fourth forward speed ratio is established with the engagement of theclutches 50, 52 and the brake 59. The clutch 50 connects the planetcarrier assembly member 36 with the input shaft 17. The clutch 52connects the planet carrier assembly member 46 with the input shaft 17.The brake 59 connects the sun gear member 22 with the transmissionhousing 60. The sun gear member 42 does not rotate. The planet carrierassembly member 46, the planet carrier assembly member 36 and the ringgear member 24 rotate at the same speed as the input shaft 17. The ringgear member 34 rotates at the same speed as the planet carrier assemblymember 26. The sun gear member 22 does not rotate. The planet carrierassembly member 26 rotates at the same speed as the output shaft 19. Theplanet carrier assembly member 26, and therefore the output shaft 19,rotates at a speed determined from the speed of the ring gear member 24and the ring gear/sun gear tooth ratio of the planetary gear set 20. Thenumerical value of the fourth forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratio of the planetary gear set20.

The fifth forward speed ratio is established with the engagement of theclutches 50, 52 and 57. The clutch 50 connects the planet carrierassembly member 36 with the input shaft 17. The clutch 52 connects theplanet carrier assembly member 46 with the input shaft 17. The clutch 57connects the ring gear member 44 with the sun gear member 32. The planetcarrier assembly member 46, the planet carrier assembly member 36, andthe ring gear member 24 rotate at the same speed as the input shaft 17.The sun gear member 42 does not rotate. The ring gear member 44 rotatesat the same speed as the sun gear member 32. The ring gear member 44rotates at a speed determined from the speed of the planet carrierassembly member 46 and the ring gear/sun gear tooth ratio of theplanetary gear set 40. The ring gear member 34 and the planet carrierassembly member 26 rotate at the same speed as the output shaft 19. Thering gear member 34, and therefore the output shaft 19, rotates at aspeed determined from the speed of the planet carrier assembly member36, the speed of the sun gear member 32 and the ring gear/sun gear toothratio of the planetary gear set 30. The numerical value of the fifthforward speed ratio is determined utilizing the ring gear/sun gear toothratios of the planetary gear sets 30 and 40.

The sixth forward speed ratio is established with the engagement of theclutches 50, 52 and 56. In this configuration, the input shaft 17 isdirectly connected to the output shaft 19. The numerical value of thesixth forward speed ratio is 1.

The seventh forward speed ratio is established with the engagement ofthe clutches 50, 54 and 56. The clutch 50 connects the planet carrierassembly member 36 with the input shaft 17. The clutch 54 connects thering gear member 44 with the input shaft 17. The clutch 56 connects theplanet carrier assembly member 46 with the sun gear member 32. The ringgear member 44, the planet carrier assembly member 36, and the ring gearmember 24 rotate at the same speed as the input shaft 17. The planetcarrier assembly member 46 rotates at the same speed as the sun gearmember 32. The sun gear member 42 does not rotate. The planet carrierassembly member 46 rotates at a speed determined from the speed of thering gear member 44 and the ring gear/sun gear tooth ratio of theplanetary gear set 40. The ring gear member 34 and the planet carrierassembly member 26 rotate at the same speed as the output shaft 19. Thering gear member 34, and therefore the output shaft 19, rotates at aspeed determined from the speed of the planet carrier assembly member36, the speed of the sun gear member 32 and the ring gear/sun gear toothratio of the planetary gear set 30. The numerical value of the seventhforward speed ratio is determined utilizing the ring gear/sun gear toothratios of the planetary gear sets 30 and 40.

The eighth forward speed ratio is established with the engagement of theclutches 50, 56 and 57. The clutch 50 connects the planet carrierassembly member 36 with the input shaft 17. The clutch 56 connects theplanet carrier assembly member 46 with the sun gear member 32. Theclutch 57 connects the ring gear member 44 with the sun gear member 32.The sun gear member 42 does not rotate. The planet carrier assemblymember 46 and the ring gear member 44 rotate at the same speed as thesun gear member 32. The planet carrier assembly member 36 and the ringgear member 24 rotate at the same speed as the input shaft 17. The ringgear member 34 and the planet carrier assembly member 26 rotate at thesame speed at the output shaft 19. The ring gear member 34, andtherefore the output shaft 19, rotates at a speed determined from thespeed of the planet carrier assembly member 36, the speed of the sungear member 32 and the ring gear/sun gear tooth ratio of the planetarygear set 30. The numerical value of the eighth forward speed ratio isdetermined utilizing the ring gear/sun gear tooth ratio of the planetarygear set 30.

As set forth above, the engagement schedule for the torque-transmittingmechanisms is shown in the truth table of FIG. 1 b. This truth tablealso provides an example of speed ratios that are available utilizingthe ring gear/sun gear tooth ratios given by way of example in FIG. 1 b.The N_(R1)/N_(S1) value is the tooth ratio of the planetary gear set 20;the N_(R2)/N_(S2) value is the tooth ratio of the planetary gear set 30;and the N_(R3)/N_(S3) value is the tooth ratio of the planetary gear set40. Also, the chart of FIG. 1 b describes the ratio steps that areattained utilizing the sample of tooth ratios given. For example, thestep ratio between the first and second forward speed ratios is 1.46,while the step ratio between the reverse (Reverse) and first forwardratio is −0.82. As may be seen in the truth table of FIG. 1 b, each ofthe single step forward interchanges is of the single transitionvariety. It should also be noted that the torque-transmitting mechanisms54, 56 remain engaged through the neutral condition, thus simplifyingthe forward/reverse interchange.

FIG. 2 a shows a powertrain 110 having a conventional engine 12, aplanetary transmission 114, and a conventional final drive mechanism 16.The planetary transmission 114 includes an input shaft 17 continuouslyconnected with the engine 12, a planetary gear arrangement 118, and anoutput shaft 19 continuously connected with the final drive mechanism16. The planetary gear arrangement 118 includes three planetary gearsets 120, 130 and 140.

The planetary gear set 120 includes a sun gear member 122, a ring gearmember 124, and a planet carrier assembly member 126. The planet carrierassembly 126 includes a plurality of pinion gears 127 rotatably mountedon a carrier member 129 and disposed in meshing relationship with boththe sun gear member 122 and the ring gear member 124.

The planetary gear set 130 includes a sun gear member 132, a ring gearmember 134, and a planet carrier assembly member 136. The planet carrierassembly member 136 includes a plurality of pinion gears 137 rotatablymounted on a carrier member 139 and disposed in meshing relationshipwith both the sun gear member 132 and the ring gear member 134.

The planetary gear set 140 includes a sun gear member 142, a ring gearmember 144, and a planet carrier assembly member 146. The planet carrierassembly member 146 includes a plurality of pinion gears 147 rotatablymounted on a carrier member 149 and disposed in meshing relationshipwith both the sun gear member 142 and the ring gear member 144.

The planetary gear arrangement 118 also includes seventorque-transmitting mechanisms 150, 152, 154, 156, 157, 158 and 159. Thetorque-transmitting mechanisms 150, 152, 154, 156 and 157 arerotating-type torque-transmitting mechanisms, commonly termed clutches.The torque-transmitting mechanisms 158 and 159 are stationary-typetorque transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is not continuously connected with any planetary gearmember. The output shaft 19 is continuously connected with the ring gearmember 124. The ring gear member 124 is continuously connected with theplanet carrier assembly member 136 through the interconnecting member170. The planet carrier assembly member 126 is continuously connectedwith the ring gear member 134 through the interconnecting member 172.The sun gear member 142 is continuously connected with the transmissionhousing 160.

The planet carrier assembly member 126 is selectively connectable withthe input shaft 17 through the clutch 150. The sun gear member 122 isselectively connectable with the input shaft 17 through the clutch 152.The ring gear member 144 is selectively connectable with the input shaft17 through the clutch 154. The planet carrier assembly member 126 isselectively connectable with the planet carrier assembly member 146through the clutch 156. The sun gear member 122 is selectivelyconnectable with the planet carrier assembly member 146 through theclutch 157. The sun gear member 132 is selectively connectable with thetransmission housing 160 through the brake 158. The ring gear member 144is selectively connectable with the transmission housing 160 through thebrake 159.

The truth table of FIG. 2 b describes the engagement sequence utilizedto provide eight forward speed ratios and one reverse speed ratio in theplanetary gear arrangement 118 shown in FIG. 2 a, as well as extra fifthforward speed ratio.

The truth tables given in FIGS. 2 b, 3 b, 4 b, 5 b, 6 b, 7 b, 8 b, 9 b,10 b, 11 b, 12 b and 13 b show the engagement sequences for thetorque-transmitting mechanisms to provide at least eight forward speedratios and at least one reverse ratio. As shown and described above forthe configuration in FIG. 1 a, those skilled in the art will understandfrom the respective truth tables how the speed ratios are establishedthrough the planetary gear sets identified in the written description.

As set forth above, the truth table of FIG. 2 b describes the engagementsequence of the torque-transmitting mechanisms utilized to provide thereverse drive ratio and eight forward speed ratios, as well as the extrafifth forward speed ratio. The truth table also provides an example ofthe ratios that can be attained with the family members shown in FIG. 2a utilizing the sample tooth ratios given in FIG. 2b. The N_(R1)/N_(S1)value is the tooth ratio of the planetary gear set 120; theN_(R2)/N_(S2) value is the tooth ratio of the planetary gear set 130;and the N_(R3)/N_(S3) value is the tooth ratio of the planetary gear set140. Also shown in FIG. 2 b are the ratio steps between single stepratios in the forward direction as well as the reverse to first stepratio. For example, the first to second step ratio is 1.55. As can alsobe determined from the truth table of FIG. 2 b, each of single stepforward interchanges is of the single transition variety.

Turning to FIG. 3 a, a powertrain 210 includes the engine 12, aplanetary transmission 214, and a final drive mechanism 16. Theplanetary transmission 214 includes an input shaft 17 continuouslyconnected with the engine 12, a planetary gear arrangement 218, and anoutput shaft 19 continuously connected with the final drive mechanism16. The planetary gear arrangement 218 includes three planetary gearsets 220, 230 and 240.

The planetary gear set 220 includes a sun gear member 222, a ring gearmember 224, and a planet carrier assembly member 226. The planet carrierassembly 226 includes a plurality of pinion gears 227 rotatably mountedon a carrier member 229 and disposed in meshing relationship with boththe sun gear member 222 and the ring gear member 224.

The planetary gear set 230 includes a sun gear member 232, a ring gearmember 234, and a planet carrier assembly member 236. The planet carrierassembly member 236 includes a plurality of pinion gears 237 rotatablymounted on a carrier member 239 and disposed in meshing relationshipwith both the sun gear member 232 and the ring gear member 234.

The planetary gear set 240 includes a sun gear member 242, a ring gearmember 244, and a planet carrier assembly member 246. The planet carrierassembly member 246 includes a plurality of pinion gears 247 rotatablymounted on a carrier member 249 and disposed in meshing relationshipwith both the sun gear member 242 and the ring gear member 244.

The planetary gear arrangement 218 also includes seventorque-transmitting mechanisms 250, 252, 254, 256, 257, 258 and 259. Thetorque-transmitting mechanisms 250, 252, 254, 256 and 257 are rotatingtype torque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 258 and 259 are stationary-type torquetransmitting mechanisms, commonly termed brakes or reaction clutches.

The input shaft 17 is not continuously connected with any planetary gearmember. The output shaft 19 is continuously connected with the ring gearmember 224. The planet carrier assembly member 226 is continuouslyconnected with the ring gear member 234 through the interconnectingmember 270. The ring gear member 224 is continuously connected with theplanet carrier assembly member 236 through the interconnecting member272. The interconnecting member 272 may be one component or separatecomponents. The ring gear member 244 is continuously connected with thetransmission housing 260.

The sun gear member 232 is selectively connectable with the input shaft17 through the clutch 250. The sun gear member 242 is selectivelyconnectable with the input shaft 17 through the clutch 252. The planetcarrier assembly member 226 is selectively connectable with the planetcarrier assembly member 246 through the clutch 254. The sun gear member222 is selectively connectable with the planet carrier assembly member246 through the clutch 256. The sun gear member 232 is selectivelyconnectable with the planet carrier assembly member 246 through theclutch 257. The planet carrier assembly member 226 is selectivelyconnectable with the transmission housing 260 through the brake 258. Thesun gear member 222 is selectively connectable with the transmissionhousing 260 through the brake 259.

As shown in the truth table in FIG. 3 b, the torque-transmittingmechanisms are engaged in combinations of three to establish eightforward speed ratios and a reverse speed ratio, as well as extra fourthforward speed ratio.

As previously set forth, the truth table of FIG. 3 b describes thecombinations of engagements utilized for the forward and reverse speedratios. The truth table also provides an example of speed ratios thatare available with the family member described above. These examples ofspeed ratios are determined utilizing the tooth ratios given in FIG. 3b. The N_(R1)/N_(S1) value is the tooth ratio of the planetary gear set220; the N_(R2)/N_(S2) value is the tooth ratio of the planetary gearset 230; and the N_(R3)/N_(S3) value is the tooth ratio of the planetarygear set 240. Also depicted in FIG. 3 b is a chart representing theratio steps between adjacent forward speed ratios and between the firstand reverse speed ratio. For example, the first to second ratiointerchange has a step of 1.72. As can also-be determined from the truthtable of FIG. 3 b, each of the single step forward interchanges is ofthe single transition variety. It should be noted that thetorque-transmitting mechanisms 252 and 258 remain engaged through theneutral condition, thus simplifying the forward/reverse interchange.

A powertrain 310, shown in FIG. 4 a, includes the engine 12, a planetarytransmission 314, and the final drive mechanism 16. The planetarytransmission 314 includes an input shaft 17 continuously connected withthe engine 12, a planetary gear arrangement 318, and an output shaft 19continuously connected with the final drive mechanism 16. The planetarygear arrangement 318 includes three planetary gear sets 320, 330 and340.

The planetary gear set 320 includes a sun gear member 322, a ring gearmember 324, and a planet carrier assembly member 326. The planet carrierassembly member 326 includes a plurality of pinion gears 327 rotatablymounted on a carrier member 329 and disposed in meshing relationshipwith both the sun gear member 322 and the ring gear member 324.

The planetary gear set 330 includes a sun gear member 332, a ring gearmember 334, and a planet carrier assembly member 336. The planet carrierassembly member 336 includes a plurality of pinion gears 337 rotatablymounted on a carrier member 339 and disposed in meshing relationshipwith both the sun gear member 332 and the ring gear member 334.

The planetary gear set 340 includes a sun gear member 342, a ring gearmember 344, and a planet carrier assembly member 346. The planet carrierassembly member 346 includes a plurality of pinion gears 347 rotatablymounted on a carrier member 349 and disposed in meshing relationshipwith both the sun gear member 342 and the ring gear member 344.

The planetary gear arrangement 318 also includes seventorque-transmitting mechanisms 350, 352, 354, 356, 357, 358 and 359. Thetorque-transmitting mechanisms 350, 352, 354, 356 and 357 are rotatingtype torque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 358 and 359 are stationary-type torquetransmitting mechanisms, commonly termed brakes or reaction clutches.

The input shaft 17 is not continuously connected with any planetary gearmember. The output shaft 19 is continuously connected with the ring gearmember 334. The planet carrier assembly member 326 is continuouslyconnected with the planet carrier assembly member 336 through theinterconnecting member 370. The ring gear member 324 is continuouslyconnected with the sun gear member 332 through the interconnectingmember 372. The sun gear member 342 is continuously connected with thetransmission housing 360.

The sun gear member 322 is selectively connectable with the input shaft17 through the clutch 350. The planet carrier assembly member 346 isselectively connectable with the input shaft 17 through the clutch 352.The sun gear member 332 is selectively connectable with the planetcarrier assembly member 346 through the clutch 354. The planet carrierassembly member 326 is selectively connectable with the ring gear member344 through the clutch 356. The sun gear member 322 is selectivelyconnectable with the ring gear member 344 through the clutch 357. Thesun gear member 332 is selectively connectable with the transmissionhousing 360 through the brake 358. The planet carrier assembly member336 is selectively connectable with the transmission housing 360 throughthe brake 359.

The truth table shown in FIG. 4 b describes the engagement combinationand the engagement sequence necessary to provide a reverse drive ratioand nine forward speed ratios, as well as extra fourth, fifth and sixthforward speed ratios. A sample of the numerical values for the ratios isalso provided in the truth table of FIG. 4 b. These values aredetermined utilizing the ring gear/sun gear tooth ratios also given inFIG. 4 b. The N_(R1)/N_(S1) value is the tooth ratio for the planetarygear set 320; the N_(R2)/N_(S2) value is the tooth ratio for theplanetary gear set 330; and the N_(R3)/N_(S3) value is the tooth ratiofor the planetary gear set 340. Also given in FIG. 4 b is a chartdescribing the step ratios between the adjacent forward speed ratios andthe reverse to first forward speed ratio. For example, the first tosecond forward speed ratio step is 1.46. It should be noted that thetorque-transmitting mechanisms 352 and 359 remain engaged through theneutral condition, thus simplifying the forward/reverse interchange.

A powertrain 410, shown in FIG. 5 a, includes the engine 12, a planetarytransmission 414 and the final drive mechanism 16. The planetarytransmission 414 includes a planetary gear arrangement 418, input shaft17 and output shaft 19. The planetary gear arrangement 418 includesthree simple planetary gear sets 420, 430 and 440.

The planetary gear set 420 includes a sun gear member 422, a ring gearmember 424, and a planet carrier assembly member 426. The planet carrierassembly 426 includes a plurality of pinion gears 427 rotatably mountedon a carrier member 429 and disposed in meshing relationship with boththe sun gear member 422 and the ring gear member 424.

The planetary gear set 430 includes a sun gear member 432, a ring gearmember 434, and a planet carrier assembly member 436. The planet carrierassembly member 436 includes a plurality of pinion gears 437 rotatablymounted on a carrier member 439 and disposed in meshing relationshipwith both the ring gear member 434 and the sun gear member 432.

The planetary gear set 440 includes a sun gear member 442, a ring gearmember 444, and a planet carrier assembly member 446. The planet carrierassembly member 446 includes a plurality of pinion gears 447 rotatablymounted on a carrier member 449 and disposed in meshing relationshipwith both the sun gear member 442 and the ring gear member 444.

The planetary gear arrangement 418 also includes seventorque-transmitting mechanisms 450, 452, 454,456,457,458 and 459. Thetorque-transmitting mechanisms 450, 452, 454, 456, 457 and 458 arerotating type torque-transmitting mechanisms, commonly termed clutches.The torque-transmitting mechanism 459 is a stationary-type torquetransmitting mechanism, commonly termed a brake or a reaction clutch.

The input shaft 17 is not continuously connected with any planetary gearmember. The output shaft 19 is continuously connected with the planetcarrier assembly member 426. The sun gear member 422 is continuouslyconnected with the ring gear member 434 through the interconnectingmember 470. The ring gear member 424 is continuously connected with theplanet carrier assembly member 436 through the interconnecting member472. The sun gear member 442 is continuously connected with thetransmission housing 460.

The planet carrier assembly member 436 is selectively connectable withthe input shaft 17 through the clutch 450. The sun gear member 432 isselectively connectable with the input shaft 17 through the clutch 452.The planet carrier assembly member 446 is selectively connectable withthe input shaft 17 through the clutch 454. The planet carrier assemblymember 436 is selectively connectable with the ring gear member 444through the clutch 456. The ring gear member 434 is selectivelyconnectable with the planet carrier assembly member 446 through theclutch 457. The sun gear member 432 is selectively connectable with thering gear member 444 through the clutch 458. The planet carrier assemblymember 446 is selectively connectable with the transmission housing 460through the brake 459.

The truth table shown in FIG. 5 b describes the engagement combinationand sequence of the torque-transmitting mechanisms 450, 452, 454, 456,457, 458 and 459 that are employed to provide the forward and reversedrive ratios.

Also given in the truth table of FIG. 5 b is a set of numerical valuesthat are attainable with the present invention utilizing the ringgear/sun gear tooth ratios shown. The N_(R1)/N_(S1) value is the toothratio of the planetary gear set 420; the N_(R2)/N_(S2) value is thetooth ratio of the planetary gear set 430; and the N_(R3)/N_(S3) valueis the tooth ratio of the planetary gear set 440.

FIG. 5 b also provides a chart of the ratio steps between adjacentforward ratios and between the reverse and first forward ratio. Forexample, the ratio step between the first and second forward ratios is2.40. As can also be determined from the truth table of FIG. 5 b, eachof the single step forward interchanges is of the single transitionvariety. It should also be noted that the torque-transmitting mechanisms452 and 459 remain engaged through the neutral condition, therebysimplifying the forward/reverse interchange.

A powertrain 510, shown in FIG. 6 a, includes an engine 12, a planetarygear transmission 514 and the final drive mechanism 16. The planetarytransmission 514 includes the input shaft 17, a planetary geararrangement 518 and the output shaft 19. The planetary gear arrangement518 includes three planetary gear sets 520, 530 and 540.

The planetary gear set 520 includes a sun gear member 522, a ring gearmember 524, and a planet carrier assembly member 526. The planet carrierassembly 526 includes a plurality of pinion gears 527 rotatably mountedon a carrier member 529 and disposed in meshing relationship with boththe sun gear member 522 and the ring gear member 524.

The planetary gear set 530 includes a sun gear member 532, a ring gearmember 534, and a planet carrier assembly member 536. The planet carrierassembly member 536 includes a plurality of pinion gears 537 rotatablymounted on a carrier member 539 and disposed in meshing relationshipwith both the sun gear member 532 and the ring gear member 534.

The planetary gear set 540 includes a sun gear member 542, a ring gearmember 544, and a planet carrier assembly member 546. The planet carrierassembly member 546 includes a plurality of pinion gears 547 rotatablymounted on a carrier member 549 and disposed in meshing relationshipwith both the sun gear member 542 and the ring gear member 544.

The planetary gear arrangement 518 also includes seventorque-transmitting mechanisms 550, 552, 554, 556, 557, 558 and 559. Thetorque-transmitting mechanisms 550, 552, 554, 556, 557 and 558 arerotating type torque-transmitting mechanisms, commonly termed clutches.The torque-transmitting mechanism 559 is a stationary-type torquetransmitting mechanism, commonly termed a brake or a reaction clutch.

The input shaft 17 is not continuously connected with any planetary gearmember. The output shaft 19 is continuously connected with the ring gearmember 534. The planet carrier assembly member 526 is continuouslyconnected with the planet carrier assembly member 536 through theinterconnecting member 570. The ring gear member 524 is continuouslyconnected with the sun gear member 532 through the interconnectingmember 572. The sun gear member 542 is continuously connected with thetransmission housing 560.

The sun gear member 532 is selectively connectable with the input shaft17 through the clutch 550. The sun gear member 522 is selectivelyconnectable with the input shaft 17 through the clutch 552. The planetcarrier assembly member 546 is selectively connectable with the inputshaft 17 through the clutch 554. The sun gear member 532 is selectivelyconnectable with the ring gear member 544 through the clutch 556. Thesun gear member 532 is selectively connectable with the planet carrierassembly member 546 through the clutch 557. The planet carrier assemblymember 536 is selectively connectable with the ring gear member 544through the clutch 558. The ring gear member 544 is selectivelyconnectable with the transmission housing 560 through the brake 559.

The truth table shown in FIG. 6 b describes the engagement sequence andcombination of the torque-transmitting mechanisms to provide a reversespeed ratio and eight forward speed ratios. The chart of FIG. 6 bdescribes the ratio steps between adjacent forward speed ratios and theratio step between the reverse and first forward speed ratio.

The sample speed ratios given in the truth table are determinedutilizing the tooth ratio values also given in FIG. 6 b. TheN_(R1)/N_(S1) value is the tooth ratio of the planetary gear set 520;the N_(R2)/N_(S2) value is the tooth ratio of the planetary gear set530; and the N_(R3)/N_(S3) value is the tooth ratio of the planetarygear set 540. As can also be determined from the truth table of FIG. 6b, each of the single step forward interchanges is of the singletransmission variety. It should also be noted that thetorque-transmitting mechanisms 558 and 559 remain engaged through theneutral condition, thereby simplifying the forward/reverse interchange.

A powertrain 610, shown in FIG. 7 a, has the engine 12, a planetarytransmission 614 and the final drive mechanism 16. The planetarytransmission 614 includes the input shaft 17, a planetary geararrangement 618 and the output shaft 19. The planetary gear arrangement618 includes three planetary gear sets 620, 630 and 640.

The planetary gear set 620 includes a sun gear member 622, a ring gearmember 624, and a planet carrier assembly member 626. The planet carrierassembly 626 includes a plurality of pinion gears 627 rotatably mountedon a carrier member 629 and disposed in meshing relationship with boththe sun gear member 622 and the ring gear member 624.

The planetary gear set 630 includes a sun gear member 632, a ring gearmember 634, and a planet carrier assembly member 636. The planet carrierassembly member 636 includes a plurality of pinion gears 637 rotatablymounted on a carrier member 639 and disposed in meshing relationshipwith both the sun gear member 632 and the ring gear member 634.

The planetary gear set 640 includes a sun gear member 642, a ring gearmember 644, and a planet carrier assembly member 646. The planet carrierassembly member 646 includes a plurality of pinion gears 647 rotatablymounted on a carrier member 649 and disposed in meshing relationshipwith both the sun gear member 642 and the ring gear member 644.

The planetary gear arrangement 618 also includes seventorque-transmitting mechanisms 650, 652, 654, 656, 657, 658 and 659. Thetorque-transmitting mechanisms 650, 652, 654, 656, 657, 658 and 659 arerotating type torque-transmitting mechanisms, commonly termed clutches.

The input shaft 17 is not continuously connected with any planetary gearmember. The output shaft 19 is continuously connected with the planetcarrier assembly member 626. The sun gear member 622 is continuouslyconnected with the ring gear member 634 through the interconnectingmember 670. The ring gear member 624 is continuously connected with theplanet carrier assembly member 636 through the interconnecting member672. The sun gear member 642 is continuously connected with thetransmission housing 660.

The planet carrier assembly member 636 is selectively connectable withthe input shaft 17 through the clutch 650. The sun gear member 632 isselectively connectable with the input shaft 17 through the clutch 652.The planet carrier assembly member 646 is selectively connectable withthe input shaft 17 through the clutch 654. The planet carrier assemblymember 636 is selectively connectable with the ring gear member 644through the clutch 656. The ring gear member 634 is selectivelyconnectable with the planet carrier assembly member 646 through theclutch 657. The sun gear member 632 is selectively connectable with thering gear member 644 through the clutch 658. The sun gear member 642 isselectively connectable with the planet carrier assembly member 646through the clutch 659.

The truth table shown in FIG. 7 b describes the combination oftorque-transmitting mechanism engagements that will provide a reversedrive ratio and nine forward speed ratios (as well as extra third, twoextra fourth and an extra sixth ratio), and as the sequence of theseengagements and interchanges. The torque-transmitting mechanisms 652 and659 remain engaged through the neutral condition, thereby simplifyingthe forward/reverse interchange. As can be determined from the truthtable of FIG. 7 b, each of the single step forward interchanges is ofthe single transition variety.

The ratio values given are by way of example and are establishedutilizing the ring gear/sun gear tooth ratios given in FIG. 7 b. Forexample, the N_(R1)/N_(S1) value is the tooth ratio of the planetarygear set 620; the N_(R2)/N_(S2) value is the tooth ratio of theplanetary gear set 630; and the N_(R3)/N_(S3) value is the tooth ratioof the planetary gear set 640. The ratio steps between adjacent forwardratios and the reverse to first ratio are also given in FIG. 7 b.

A powertrain 710, shown in FIG. 8 a, has the conventional engine 12, aplanetary transmission 714, and the conventional final drive mechanism16. The engine 12 is drivingly connected with the planetary transmission714 through the input shaft 17. The planetary transmission 714 isdrivingly connected with the final drive mechanism 16 through the outputshaft 19. The planetary transmission 714 includes a planetary geararrangement 718 that has a first planetary gear set 720, a secondplanetary gear set 730, and a third planetary gear set 740.

The planetary gear set 720 includes a sun gear member 722, a ring gearmember 724, and a planet carrier assembly member 726. The planet carrierassembly 726 includes a plurality of pinion gears 727 rotatably mountedon a carrier member 729. The pinion gears 727 are disposed in meshingrelationship with both the sun gear member 722 and the ring gear member724.

The planetary gear set 730 includes a sun gear member 732, a ring gearmember 734, and a planet carrier assembly member 736. The planet carrierassembly member 736 includes a plurality of pinion gears 737 rotatablymounted on a carrier member 739 and disposed in meshing relationshipwith both the sun gear member 732 and the ring gear member 734.

The planetary gear set 740 includes a sun gear member 742, a ring gearmember 744, and a planet carrier assembly member 746. The planet carrierassembly member 746 includes a plurality of pinion gears 747 rotatablymounted on a carrier member 749 and disposed in meshing relationshipwith both the sun gear member 742 and the ring gear member 744.

The planetary gear arrangement 718 also includes seventorque-transmitting mechanisms 750, 752, 754, 756, 757, 758 and 759. Thetorque-transmitting mechanisms 750, 752, 754, 756, 757, 758 and 759 arerotating type torque-transmitting mechanisms, commonly termed clutches.

The input shaft 17 is not continuously connected with any planetary gearmember. The output shaft 19 is continuously connected with the ring gearmember 734. The planet carrier assembly member 726 is continuouslyconnected with the planet carrier assembly member 736 through theinterconnecting member 770. The ring gear member 724 is continuouslyconnected with the sun gear member 732 through the interconnectingmember 772. The sun gear member 742 is continuously connected with thetransmission housing 760.

The sun gear member 732 is selectively connectable with the input shaft17 through the clutch 750. The sun gear member 722 is selectivelyconnectable with the input shaft 17 through the clutch 752. The planetcarrier assembly member 746 is selectively connectable with the inputshaft 17 through the clutch 754. The sun gear member 732 is selectivelyconnectable with the ring gear member 744 through the clutch 756. Thesun gear member 732 is selectively connectable with the planet carrierassembly member 746 through the clutch 757. The planet carrier assemblymember 736 is selectively connectable with the ring gear member 744through the clutch 758. The ring gear member 744 is selectivelyconnectable with the planet carrier assembly member 746 through theclutch 759.

The truth table of FIG. 8 b defines the torque-transmitting mechanismengagement sequence utilized for each of the forward and reverse speedratios. Also given in the truth table is a set of numerical values thatare attainable with the present invention utilizing the ring gear/sungear tooth ratios given in FIG. 8 b. The N_(R1)/N_(S1) value is thetooth ratio of the planetary gear set 720; the N_(R2)/N_(S2) value isthe tooth ratio of the planetary gear set 730; and the N_(R3)/N_(S3)value is the tooth ratio of the planetary gear set 740.

FIG. 8 b also provides a chart of the ratio steps between adjacentforward ratios and between the reverse and first forward ratio. Forexample, the ratio step between the first and second forward ratios is2.20. As can be determined from the truth table of FIG. 8 b, each of thesingle step forward interchanges is of the single transition variety.Additionally, it should be noted that torque-transmitting mechanisms 758and 759 remain engaged through the neutral condition, therebysimplifying the forward/reverse interchange.

A powertrain 810, shown in FIG. 9 a, has the conventional engine 12, aplanetary transmission 814, and the final drive mechanism 16. The engine12 is drivingly connected with the planetary transmission 814 throughthe input shaft 17. The planetary transmission 814 is drivinglyconnected with the final drive mechanism 16 through the output shaft 19.The planetary transmission 814 includes a planetary gear arrangement 818that has a first planetary gear set 820, a second planetary gear set830, and a third planetary gear set 840.

The planetary gear set 820 includes a sun gear member 822, a ring gearmember 824, and a planet carrier assembly member 826. The planet carrierassembly 826 includes a plurality of pinion gears 827 rotatably mountedon a carrier member 829 and disposed in meshing relationship with boththe sun gear member 822 and the ring gear member 824.

The planetary gear set 830 includes a sun gear member 832, a ring gearmember 834, and a planet carrier assembly member 836. The planet carrierassembly member 836 includes a plurality of pinion gears 837 rotatablymounted on a carrier member 839 and disposed in meshing relationshipwith both the sun gear member 832 and the ring gear member 834.

The planetary gear set 840 includes a sun gear member 842, a ring gearmember 844, and a planet carrier assembly member 846. The planet carrierassembly member 846 includes a plurality of pinion gears 847 rotatablymounted on a carrier member 849 and disposed in meshing relationshipwith both the ring gear member 844 and the sun gear member 842.

The planetary gear arrangement 818 also includes seventorque-transmitting mechanisms 850, 852, 854, 856, 857, 858 and 859. Thetorque-transmitting mechanisms 850, 852, 854 and 856 are rotating typetorque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 857, 858 and 859 are stationary-typetorque transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is not continuously connected with any planetary gearmember. The output shaft 19 is continuously connected with the ring gearmember 824. The sun gear member 822 is continuously connected with thering gear member 834 through the interconnecting member 870. The planetcarrier assembly member 826 is continuously connected with the planetcarrier assembly member 836 through the interconnecting member 872. Thering gear member 844 is continuously connected with the transmissionhousing 860.

The sun gear member 832 is selectively connectable with the input shaft17 through the clutch 850. The sun gear member 842 is selectivelyconnectable with the input shaft 17 through the clutch 852. The planetcarrier assembly member 836 is selectively connectable with the planetcarrier assembly member 846 through the clutch 854. The ring gear member834 is selectively connectable with the planet carrier assembly member846 through the clutch 856. The planet carrier assembly member 826 isselectively connectable with the transmission housing 860 through thebrake 857. The ring gear member 834 is selectively connectable with thetransmission housing 860 through the brake 858. The sun gear member 832is selectively connectable with the transmission housing 860 through thebrake 859.

The truth table shown in FIG. 9 b defines the torque-transmittingmechanism engagement sequence that provides the reverse speed ratio andeight forward speed ratios as well as the extra fourth forward speedratio shown in the truth table and available with the planetary geararrangement 818. A sample of numerical values for the individual ratiosis also given in the truth table of FIG. 9 b. These numerical valueshave been calculated using the ring gear/sun gear tooth ratios alsogiven by way of example in FIG. 9 b. The N_(R1)/N_(S1) value is thetooth ratio of the planetary gear set 820; the N_(R2)/N_(S2) value isthe tooth ratio of the planetary gear set 830; and the N_(R3)/N_(S3)value is the tooth ratio of the planetary gear set 840. FIG. 9 b alsodescribes the ratio steps between adjacent forward ratios and betweenthe reverse and first forward ratio. As can also be determined from thetruth table of FIG. 9 b, each of the single step forward interchanges isof the single transition variety. It should also be noted that thetorque-transmitting mechanisms 852 and 856 remain engaged through theneutral condition, thereby simplifying the forward/reverse interchange.

The powertrain 910, shown in FIG. 10 a, includes the conventional engine12, a planetary transmission 914, and the conventional final drivemechanism 16. The engine 12 is drivingly connected with the planetarytransmission 914 through the input shaft 17. The planetary transmission914 is drivingly connected with the final drive mechanism 16 through theoutput shaft 19. The planetary transmission 914 includes a planetarygear arrangement 918 that has a first planetary gear set 920, a secondplanetary gear set 930, and a third planetary gear set 940.

The planetary gear set 920 includes a sun gear member 922, a ring gearmember 924, and a planet carrier assembly member 926. The planet carrierassembly member 926 includes a plurality of pinion gears 927 that arerotatably mounted on a carrier member 929 and disposed in meshingrelationship with both the sun gear member 922 and the ring gear member924, respectively.

The planetary gear set 930 includes a sun gear member 932, a ring gearmember 934, and a planet carrier assembly member 936. The planet carrierassembly member 936 includes a plurality of pinion gears 937 rotatablymounted on a carrier member 939 and disposed in meshing relationshipwith both the ring gear member 934 and the sun gear member 932.

The planetary gear set 940 includes a sun gear member 942, a ring gearmember 944, and a planet carrier assembly member 946. The planet carrierassembly member 946 includes a plurality of pinion gears 947 rotatablymounted on a carrier member 949 and disposed in meshing relationshipwith both the sun gear member 942 and the ring gear member 944.

The planetary gear arrangement 918 also includes seventorque-transmitting mechanisms 950, 952, 954, 956, 957, 958 and 959. Thetorque-transmitting mechanisms 950, 952, 954 and 956 are rotating-typetorque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 957, 958 and 959 are stationary-typetorque-transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is not continuously connected with any planetary gearmember. The output shaft 19 is continuously connected with the planetcarrier assembly member 926. The planet carrier assembly member 926 iscontinuously connected with the ring gear member 934 through theinterconnecting member 970. The ring gear member 924 is continuouslyconnected with the sun gear member 932 through the interconnectingmember 972. The ring gear member 944 is continuously connected with thetransmission housing 960.

The sun gear member 922 is selectively connectable with the input shaft17 through the clutch 950. The sun gear member 942 is selectivelyconnectable with the input shaft 17 through the clutch 952. The planetcarrier assembly member 926 is selectively connectable with the planetcarrier assembly member 946 through the clutch 954. The sun gear member932 is selectively connectable with the planet carrier assembly member946 through the clutch 956. The planet carrier assembly member 936 isselectively connectable with the transmission housing 960 through thebrake 957. The sun gear member 922 is selectively connectable with thetransmission housing 960 through the brake 958. The sun gear member 932is selectively connectable with the transmission housing 960 through thebrake 959.

The truth table of FIG. 10 b describes the torque-transmitting mechanismengagement sequence utilized to provide a reverse speed ratio and eightforward speed ratios as well as an extra fourth forward speed ratio. Thetruth table also provides a set of examples for the ratios for each ofthe reverse and forward speed ratios. These numerical values have beendetermined utilizing the ring gear/sun gear tooth ratios given in FIG.10 b. The N_(R1)/N_(S1) value is the tooth ratio of the planetary gearset 920; the N_(R2)/N_(S2) value is the tooth ratio of the planetarygear set 930; and the N_(R3)/N_(S3) value is the tooth ratio of theplanetary gear set 940. As can also be determined from the truth tableof FIG. 10 b, each of the single step forward interchanges is of thesingle transition variety. Additionally, it should also be noted thatthe torque-transmitting mechanisms 952 and 956 remain engaged throughthe neutral condition, thereby simplifying the forward/reverseinterchange.

A powertrain 1010, shown in FIG. 11 a, includes the conventional engine12, a planetary transmission 1014, and the conventional final drivemechanism 16. The engine is drivingly connected with the planetarytransmission 1014 through the input shaft 17. The planetary transmission1014 is drivingly connected with the final drive mechanism 16 throughthe output shaft 19. The planetary transmission 1014 includes aplanetary gear arrangement 1018 that has a first planetary gear set1020, a second planetary gear set 1030, and a third planetary gear set1040.

The planetary gear set 1020 includes a sun gear member 1022, a ring gearmember 1024, and a planet carrier assembly member 1026. The planetcarrier assembly 1026 includes a plurality of pinion gears 1027rotatably mounted on a carrier member 1029 and disposed in meshingrelationship with both the sun gear member 1022 and the ring gear member1024.

The planetary gear set 1030 includes a sun gear member 1032, a ring gearmember 1034, and a planet carrier assembly member 1036. The planetcarrier assembly member 1036 includes a plurality of pinion gears 1037rotatably mounted on a carrier member 1039 and disposed in meshingrelationship with both the ring gear member 1034 and the sun gear member1032.

The planetary gear set 1040 includes a sun gear member 1042, a ring gearmember 1044, and a planet carrier assembly member 1046. The planetcarrier assembly member 1046 includes a plurality of pinion gears 1047rotatably mounted on a carrier member 1049 and disposed in meshingrelationship with both the ring gear member 1044 and the sun gear member1042.

The planetary gear arrangement 1018 also includes seventorque-transmitting mechanisms 1050, 1052, 1054, 1056, 1057, 1058 and1059. The torque-transmitting mechanisms 1050, 1052, 1054 and 1056 arerotating-type torque-transmitting mechanisms, commonly termed clutches.The torque-transmitting mechanisms 1057, 1058 and 1059 arestationary-type torque-transmitting mechanisms, commonly termed brakesor reaction clutches.

The input shaft 17 is not continuously connected with any planetary gearmember. The output shaft 19 is continuously connected with the planetcarrier assembly member 1026. The ring gear member 1024 is continuouslyconnected with the planet carrier assembly member 1036 through theinterconnecting member 1070. The sun gear member 1022 is continuouslyconnected with the ring gear member 1034 through the interconnectingmember 1072. The planet carrier assembly member 1046 is continuouslyconnected with the transmission housing 1060.

The ring gear member 1034 is selectively connectable with the inputshaft 17 through the clutch 1050. The ring gear member 1044 isselectively connectable with the input shaft 17 through the clutch 1052.The planet carrier assembly member 1036 is selectively connectable withthe ring gear member 1044 through the clutch 1054. The sun gear member1032 is selectively connectable with the sun gear member 1042 throughthe clutch 1056. The sun gear member 1022 is selectively connectablewith the transmission housing 1060 through the brake 1057. The ring gearmember 1024 is selectively connectable with the transmission housing1060 through the brake 1058. The sun gear member 1032 is selectivelyconnectable with the transmission housing 1060 through the brake 1059.

The truth table shown in FIG. 11 b describes the engagement combinationsand the engagement sequence necessary to provide a reverse drive ratioand eight forward speed ratios as well as an extra fifth forward speedratio. A sample of the numerical values for the ratios is also providedin the truth table of FIG. 11 b. These values are determined utilizingthe ring gear/sun gear tooth ratios also given in FIG. 11 b. TheN_(R1)/N_(S1) value is the tooth ratio for the planetary gear set 1020;the N_(R2)/N_(S2) value is the tooth ratio for the planetary gear set1030; and the N_(R3)/N_(S3) value is the tooth ratio for the planetarygear set 1040. Also given in FIG. 11 b is a chart describing the stepratios between the adjacent forward speed ratios and the reverse tofirst forward speed ratio. As can also be determined from the truthtable of FIG. 11 b, each of the single step forward interchanges is ofthe single transition variety. Additionally, it should be noted that thetorque-transmitting mechanisms 1052 and 1056 remain engaged through theneutral condition, thereby simplifying the forward/reverse interchange.

A powertrain 1110, shown in FIG. 12 a, includes the conventional engine12, a planetary transmission 1114, and the conventional final drivemechanism 16. The engine is drivingly connected with the planetarytransmission 1114 through the input shaft 17. The planetary transmission1114 is drivingly connected with the final drive mechanism 16 throughthe output shaft 19. The planetary transmission 1114 includes aplanetary gear arrangement 1118 that has a first planetary gear set1120, a second planetary gear set 1130, and a third planetary gear set1140.

The planetary gear set 1120 includes a sun gear member 1122, a ring gearmember 1124, and a planet carrier assembly member 1126. The planetcarrier assembly member 1126 includes a plurality of pinion gears 1127rotatably mounted on a carrier member 1129 and disposed in meshingrelationship with both the sun gear member 1122 and the ring gear member1124.

The planetary gear set 1130 includes a sun gear member 1132, a ring gearmember 1134, and a planet carrier assembly member 1136. The planetcarrier assembly member 1136 includes a plurality of pinion gears 1137rotatably mounted on a carrier member 1139 and disposed in meshingrelationship with both the sun gear member 1132 and the ring gear member1134.

The planetary gear set 1140 includes a sun gear member 142, a ring gearmember 1144, and a planet carrier assembly member 1146. The planetcarrier assembly member 1146 includes a plurality of pinion gears 1147rotatably mounted on a carrier member 1149 and disposed in meshingrelationship with the ring gear member 1144 and the sun gear member1142.

The planetary gear arrangement 1118 also includes seventorque-transmitting mechanisms 1150, 1152, 1154, 1156, 1157, 1158 and1159. The torque-transmitting mechanisms 1150, 1152, 1154, 1156 and 1157are rotating type torque-transmitting mechanisms, commonly termedclutches. The torque-transmitting mechanisms 1158 and 1159 arestationary type torque-transmitting mechanisms commonly termed brakes orreaction clutches.

The input shaft 17 is not continuously connected with any planetary gearmember. The output shaft 19 is continuously connected with the ring gearmember 1134. The planet carrier assembly member 1126 is continuouslyconnected with the planet carrier assembly member 1136 through theinterconnecting member 1170. The ring gear member 1124 is continuouslyconnected with the sun gear member 1132 through the interconnectingmember 1172. The sun gear member 1142 is continuously connected with thetransmission housing 1160.

The sun gear member 1122 is selectively connectable with the input shaft17 through the clutch 1150. The ring gear member 1144 is selectivelyconnectable with the input shaft 17 through the clutch 1152. The planetcarrier assembly member 1146 is selectively connectable with the inputshaft 17 through the clutch 1154. The planet carrier assembly member1126 is selectively connectable with the ring gear member 1144 throughthe clutch 1156. The sun gear member 1132 is selectively connectablewith the planet carrier assembly member 1146 through the clutch 1157.The sun gear member 1136 is selectively connectable with thetransmission housing 1160 through the brake 1158. The sun gear member1132 is selectively connectable with the transmission housing 1160through the brake 1159.

The truth table shown in FIG. 12 b describes the engagement combinationsand the engagement sequence necessary to provide two reverse driveratios and eight forward speed ratios as well as an extra sixth and anextra seventh forward speed ratio. A sample of the numerical values forthe ratios is also provided in the truth table of FIG. 12 b. The valuesare determined utilizing the ring gear/sun gear tooth ratios also givenin FIG. 12 b. The N_(R1)/S_(R1) value is the tooth ratio of theplanetary gear set 1120; the N_(R2)/S_(R2) value is the tooth ratio ofthe planetary gear set 1130; and the N_(R3)/S_(R3) value is the toothratio of the planetary gear set 1140. Also given in FIG. 12 b is a chartdescribing the step ratios between the adjacent forward speed ratios andthe reverse to first forward speed ratio. For example, step ratiobetween the first and second forward speed ratios is 2.22. As can alsobe determined from the truth table of FIG. 12 b, each of the single stepforward interchanges is of the single transition variety. It should alsobe noted that the torque-transmitting mechanisms 1157 and 1158 remainengaged through the neutral condition, thereby simplifying theforward/reverse interchange.

A powertrain 1210, shown in FIG. 13 a, includes the conventional engine12, a planetary transmission 1214, and the conventional final drivemechanism 16. The engine is drivingly connected with the planetarytransmission 1214 through the input shaft 17. The planetary transmission1214 is drivingly connected with the final drive mechanism 16 throughthe output shaft 19. The planetary transmission 1214 includes aplanetary gear arrangement 1218 that has a first planetary gear set1220, a second planetary gear set 1230, and a third planetary gear set1240.

The planetary gear set 1220 includes a sun gear member 1222, a ring gearmember 1224, and a planet carrier assembly member 1226. The planetcarrier assembly member 1226 includes a plurality of pinion gears 1227rotatably mounted on a carrier member 1229 and disposed in meshingrelationship with the sun gear member 1222. Pinion gears 1228 aredisposed in meshing relationship with both the ring gear member 1224 andthe pinion gears 1227.

The planetary gear set 1230 includes a sun gear member 1232, a ring gearmember 1234, and a planet carrier assembly member 1236. The planetcarrier assembly member 1236 includes a plurality of pinion gears 1237rotatably mounted on a carrier member 1239 and disposed in meshingrelationship with both the ring gear member 1234 and the sun gear member1232.

The planetary gear set 1240 includes a sun gear member 1242, a ring gearmember 1244, and a planet carrier assembly member 1246. The planetcarrier assembly member 1246 includes a plurality of pinion gears 1247rotatably mounted on a carrier member 1249 and disposed in meshingrelationship with both the sun gear member 1242 and the ring gear member1244.

The planetary gear arrangement 1218 also includes seventorque-transmitting mechanisms 1250, 1252, 1254, 1256, 1257, 1258 and1259. The torque-transmitting mechanisms 1250, 1252, 1254, 1256 and 1257are rotating type torque-transmitting mechanisms, commonly termedclutches. The torque-transmitting mechanisms 1258 and 1259 arestationary type torque-transmitting mechanisms, commonly termed a brakesor reaction clutches.

The input shaft 17 is not continuously connected with any planetary gearmember. The output shaft 19 is continuously connected with the ring gearmember 1224. The planet carrier assembly member 1226 is continuouslyconnected with the sun gear member 1232 through the interconnectingmember 1270. The ring gear member 1224 is continuously connected withthe ring gear member 1234 through the interconnecting member 1270. Thesun gear member 1242 is continuously connected with the transmissionhousing 1260.

The sun gear member 1222 is selectively connectable with the input shaft17 through the clutch 1250. The planet carrier assembly member 1246 isselectively connectable with the input shaft 17 through the clutch 1252.The sun gear member 1232 is selectively connectable with the planetcarrier assembly member 1246 through the clutch 1254. The sun gearmember 1232 is selectively connectable with the ring gear member 1244through the clutch 1256. The planet carrier assembly member 1236 isselectively connectable with the ring gear member 1244 through theclutch 1257. The planet carrier assembly member 1236 is selectivelyconnectable with the transmission housing 1260 through the brake 1258.The planet carrier assembly member 1246 is selectively connectable withthe transmission housing 1260 through the brake 1259.

The truth table shown in FIG. 13 b describes the engagement combinationsand the engagement sequence necessary to provide two reverse driveratios and eight forward speed ratios. A sample of the numerical valuesfor the ratios is also provided in the truth table of FIG. 13 b. Thesevalues are determined utilizing the ring gear/sun gear tooth ratios alsogiven in FIG. 13 b. The N_(R1)/S_(R1) value is the tooth ratio of theplanetary gear set 1220; the N_(R2)/S_(R2) value is the tooth ratio ofthe planetary gear set 1230; and the N_(R3)/S_(R3) value is the toothratio of the planetary gear set 1240. Also given in FIG. 13 b is a chartdescribing the step ratios between the adjacent forward speed ratios andthe reverse to first forward speed ratio. As can be determined from thetruth table of FIG. 13 b, each of the single step forward interchangesis of the single transition variety. Additionally, it should be notedthat the torque-transmitting mechanism 1258 remains engaged through theneutral condition, thereby simplifying the forward/reverse interchange.

While the best modes for carrying out the invention have been describedin detail, those familiar with the art to which this invention relateswill recognize various alternative designs and embodiments forpracticing the invention within the scope of the appended claims.

1. A multi-speed transmission comprising: an input shaft; an outputshaft; first, second and third planetary gear sets each having first,second and third members; said output shaft being continuouslyinterconnected with a member of said planetary gear sets, and said inputshaft not being continuously interconnected with any member of saidplanetary gear sets; a first interconnecting member continuouslyinterconnecting said first member of said first planetary gear set withsaid first member of said second planetary gear set; a secondinterconnecting member continuously interconnecting said second memberof said first planetary gear set with said second member of said secondplanetary gear set; said first member of said third planetary gear setbeing continuously interconnected with a stationary member; a firsttorque-transmitting mechanism selectively interconnecting a member ofsaid third planetary gear set with said input shaft; a secondtorque-transmitting mechanism selectively interconnecting a member ofsaid first or second planetary gear set with said input shaft; a thirdtorque-transmitting mechanism selectively interconnecting a member ofsaid first, second or third planetary gear set with said input shaft orwith another member of said first, second or third planetary gear set; afourth torque-transmitting mechanism selectively interconnecting amember of said third planetary gear set with a member of said first orsecond planetary gear set; a fifth torque-transmitting mechanismselectively interconnecting a member of said first or second planetarygear set with a member of said third planetary gear set, or with saidstationary member; a sixth torque-transmitting mechanism selectivelyinterconnecting a member of said first or second planetary gear set withanother member of said first, second or third planetary gear set, orwith said stationary member; a seventh torque-transmitting mechanismselectively interconnecting a member of said first, second or thirdplanetary gear set with another member of said first, second or thirdplanetary gear set, or with said stationary member; saidtorque-transmitting mechanisms being engaged in combinations of three toestablish at least eight forward speed ratios and at least one reversespeed ratio between said input shaft and said output shaft.
 2. Thetransmission defined in claim 1, wherein said first, second, third,fourth, fifth and sixth torque-transmitting mechanisms compriseclutches, and said seventh torque-transmitting mechanism comprises abrake.
 3. The transmission defined in claim 1, wherein said first,second, third and fourth torque-transmitting mechanisms compriseclutches, and said fifth, sixth and seventh torque-transmittingmechanisms comprise brakes.
 4. The transmission defined in claim 1,wherein said first, second, third, fourth and fifth torque-transmittingmechanisms comprise clutches, and said sixth and seventhtorque-transmitting mechanisms comprise brakes.
 5. The transmissiondefined in claim 1, wherein said first, second, third, fourth, fifth,sixth and seventh torque-transmitting mechanisms comprise clutches. 6.The transmission defined in claim 1, wherein planet carrier assemblymembers of each of said planetary gear sets are single-pinion carriers.7. The transmission defined in claim 1, wherein at least one planetcarrier assembly member of said planetary gear sets is a double-pinioncarrier.
 8. A multi-speed transmission comprising: an input shaft; anoutput shaft; a planetary gear arrangement having first, second andthird planetary gear sets, each planetary gear set having first, secondand third members; said output shaft being continuously interconnectedwith a member of said planetary gear sets, and said input shaft notbeing continuously interconnected with any member of said planetary gearsets; a first interconnecting member continuously interconnecting saidfirst member of said first planetary gear set with said first member ofsaid second planetary gear set; a second interconnecting membercontinuously interconnecting said second member of said first planetarygear set with said second member of said second planetary gear set; saidfirst member of said third planetary gear set being continuouslyinterconnected with a stationary member; and seven torque-transmittingmechanisms for selectively interconnecting said members of saidplanetary gear sets with said input shaft, with said stationary memberor with other members of said planetary gear sets, said seventorque-transmitting mechanisms being engaged in combinations of three toestablish at least eight forward speed ratios and at least one reversespeed ratio between said input shaft and said output shaft.
 9. Thetransmission defined in claim 8, wherein a first of said seventorque-transmitting mechanisms is operable for selectivelyinterconnecting a member of said third planetary gear set with saidinput shaft.
 10. The transmission defined in claim 8, wherein a secondof said seven torque-transmitting mechanisms is operable for selectivelyinterconnecting a member of said first or second planetary gear set withsaid input shaft.
 11. The transmission defined in claim 8, wherein athird of said seven torque-transmitting mechanisms is operable forselectively interconnecting a member of said first, second or thirdplanetary gear set with said input shaft or with another member of saidfirst, second or third planetary gear set.
 12. The transmission definedin claim 8, wherein a fourth of said seven torque-transmittingmechanisms is operable for selectively interconnecting a member of saidthird planetary gear set with a member of said first or second planetarygear set.
 13. The transmission defined in claim 8, wherein a fifth ofsaid seven torque-transmitting mechanisms is operable for selectivelyinterconnecting a member of said first or second planetary gear set witha member of said third planetary gear set, or with said stationarymember.
 14. The transmission defined in claim 8, wherein a sixth of saidseven torque-transmitting mechanisms is operable for selectivelyinterconnecting a member of said first or second planetary gear set withanother member of said first, second or third planetary gear set, orwith said stationary member.
 15. The transmission defined in claim 8,wherein a seventh of said seven torque-transmitting mechanisms isoperable for selectively interconnecting a member of said first, secondor third planetary gear set with another member of said first, second orthird planetary gear set, or with said stationary member.
 16. Thetransmission defined in claim 8, wherein planet carrier assembly membersof each of said planetary gear sets are single-pinion carriers.
 17. Thetransmission defined in claim 8, wherein at least one planet carrierassembly member of said planetary gear sets is a double-pinion carrier.